Canada thistle [Cirsium arvense (L) Scop.] response to density of Cassida rubiginosa Müller (Coleoptera: Chrysomelidae) and plant competition

Published source details Ang B.N., Kok L.T., Holtzman G.I. & Wolf D.D. (1995) Canada thistle [Cirsium arvense (L) Scop.] response to density of Cassida rubiginosa Müller (Coleoptera: Chrysomelidae) and plant competition. Biological Control, 5, 31-38.
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This study is summarised as evidence for the following.

	Action	Category
	Grow plants that compete with damaging weeds Action Link

Grow plants that compete with damaging weeds

A randomised, replicated trial in farmland in Virginia, USA (Ang et al. 1995) found that sowing plots with tall fescue Festuca arundinacea and crownvetch Coronilla varia reduced shoot weight (0.1-2.7 g/plant vs. 0.0-6.0 g/plant in control plots), reproduction (0.1-1.3 vs. 0.0-2.9 plants produced/original plant) and survival (0.0-1.6 vs. 0.8-2.8 plants surviving out of three) of creeping thistle Cirsium arvense in one year out of two. In the second year of the experiment thistle shoot weight was not affected, but plots with competitor plants had lower thistle root weight (0.0-2.6 vs. 0.5-3.3 g/plant) and root length (14.9-57.0 vs. 1.3-45.1 cm/plant). The experiment also found that the thistle-eating green tortoise beetle Cassida rubiginosa reduced thistle biomass and reproduction in both years. Plots were 8 x 10 m in blocks of two, one plot without competitor plants and one plot with tall fescue and crownvetch sown at 50 and 20 kg/ha respectively. Thistles were planted in cages in a 2 x 2 m grid, and four treatments of 0, 5, 10 or 20 green tortoise beetles were applied randomly to three plants within each plot.